Dietary inflammatory index, Mediterranean diet score, and lung cancer: a prospective study

Abstract

Purpose: To investigate prospectively the associations of Dietary Inflammatory Index (DII) and Mediterranean Diet Score (MDS) with lung cancer.

Methods: We used data from men and women aged 40-69 years at recruitment in 1990-1994, who were participants in the Melbourne Collaborative Cohort Study (n = 35,303). A total of 403 incident lung cancer cases were identified over an average 18-year follow-up. Hazard ratios (HR) were estimated using Cox regression, adjusting for smoking status and other risk factors, with age as the time metric.

Results: An inverse correlation was observed between the DII and MDS (ρ = -0.45), consistent with a higher DII being pro-inflammatory and less 'healthy,' while a high MDS reflects a 'healthier' diet. The DII was positively associated with risk of lung cancer in current smokers [HRQ4 vs Q1 = 1.70 (1.02, 2.82); Ptrend = 0.008] (p interaction between DII quartiles and smoking status = 0.03). The MDS was inversely associated with lung cancer risk overall [HR7-9 vs 0-3 = 0.64 (0.45, 0.90); Ptrend = 0.005] and for current smokers (HR7-9 vs 0-3 = 0.38 (0.19, 0.75); Ptrend = 0.005) (p interaction between MDS categories and smoking status = 0.31).

Conclusions: The MDS showed an inverse association with lung cancer risk, especially for current smokers. A high DII, indicating a more pro-inflammatory diet, was associated with risk of lung cancer only for current smokers. A healthy diet may reduce the risk of lung cancer, especially in smokers.

Keywords: Diet; Epidemiology; Inflammation; Lung cancer; Prospective; Smoking.

Fig. 1

Sequence of steps in creating the dietary inflammatory index in the Melbourne Collaborative Cohort Study